前言
搭建好前文的开发环境，已经可以进行开发。然而实际的项目中，不同环境有着不同的构建需求。这里就将开发环境和生产环境的配置单独提取出来，并做一些简单的优化。
分离不同环境公有配置
不同环境虽然有不同的构建需求，但依然有相同的部分，这里将共同部分提取出来，单独配置，其他环境再合并共有配置即可。安装webpack-merge(用于合并配置)、uglifyjs-webpack-plugin(js代码压缩，这里单独提取出来控制版本)和rimraf(跨平台删除工具)。
npm install webpack-merge uglifyjs-webpack-plugin rimraf --save-dev
接下来配置共有配置webpack.config.js。
const path = require('path');
const webpack = require('webpack');
module.exports = {
entry: ['babel-polyfill', path.resolve(__dirname, '../src/index.js')],// 指定入口文件，程序从这里开始编译,__dirname当前目录, ../表示上一级目录, ./同级目录
output: {
path: path.resolve(__dirname, '../dist'), // 输出的路径
filename: 'app/[name]_[hash:8].js', // 打包后文件
},
module: {
rules: [
{
enforce: 'pre',
test: /\.(js|jsx)$/,
loader: 'eslint-loader',
exclude: /node_modules/,
},
{
test: /\.(js|jsx)$/,
loader: 'babel-loader', // 加载器
exclude: /node_modules/,
},
{
test: /\.css$/,
use: [
{
loader: 'style-loader',
},
{
loader: 'css-loader',
},
],
},
{
test: /\.less$/,
use: [{
loader: 'style-loader',
}, {
loader: 'css-loader',
}, {
loader: 'less-loader',
options: {
sourceMap: true,
},
}],
},
],
},
};
配置开发环境webpack.dev.config.js。
const path = require('path');
const HtmlWebpackPlugin = require('html-webpack-plugin');
const webpack = require('webpack');
const merge = require('webpack-merge');
const webpackConfig = require('./webpack.config');
process.env.NODE_ENV = 'development';
module.exports = merge(webpackConfig, {
devtool: 'cheap-module-eval-source-map',
entry: [
'babel-polyfill',
'react-hot-loader/patch',
'webpack-dev-server/client?http://localhost:9090',
'webpack/hot/only-dev-server',
path.resolve(__dirname, '../src/index.js'),
],
plugins: [
new webpack.HotModuleReplacementPlugin(),
new webpack.DefinePlugin({
'process.env.NODE_ENV': JSON.stringify(process.env.NODE_ENV || 'development'),
}),
new HtmlWebpackPlugin({
template: path.resolve(__dirname, '../src/index.template.html'),
inject: true,
}),
new webpack.NoEmitOnErrorsPlugin(),
],
});
由于生产环境不需要热更新等，所以入口文件和以前的index.js有所不同。这里在src目录下新建index.prod.js，编辑如下。
/*eslint-disable*/
import React from 'react';
import { render } from 'react-dom';
import 'babel-polyfill';
import App from './App'; const renderDom = Component => {
render(
<Component />,
document.getElementById('app')
);
};
renderDom(App);
配置生产环境webpack.prod.config.js。
const path = require('path');
const HtmlWebpackPlugin = require('html-webpack-plugin');
const webpack = require('webpack');
const merge = require('webpack-merge');
const UglifyJSPlugin = require('uglifyjs-webpack-plugin');
const webpackConfig = require('./webpack.config');
process.env.NODE_ENV = 'production';
module.exports = merge(webpackConfig, {
entry: [
'babel-polyfill',
path.resolve(__dirname, '../src/index.prod.js'),
],
plugins: [
new UglifyJSPlugin({
uglifyOptions: {
output: {
comments: false,
beautify: false,
},
},
}),
new webpack.DefinePlugin({
'process.env.NODE_ENV': JSON.stringify(process.env.NODE_ENV || 'production'),
}),
new HtmlWebpackPlugin({
template: path.resolve(__dirname, '../src/index.template.html'),
inject: true,
minify: {
html5: true,
collapseWhitespace: true,
removeComments: true,
removeTagWhitespace: true,
removeEmptyAttributes: true,
removeStyleLinkTypeAttributes: true,
},
}),
],
});
配置package.json，新建三个执行脚本。
"scripts": {
"dev": "node bin/dev-server",
"build": "npm run clean && webpack --config webpack/webpack.prod.config.js",
"devbuild": "npm run clean && webpack --config webpack/webpack.dev.config.js",
"clean": "rimraf dist"
}
# 启动开发调试
npm run dev
# 开发环境构建
npm run devbuild
# 生产环境构建
npm run build
打包简单优化
我们在构建的时候，往往希望自己的代码和第三方库分离开来，修改webpack.config.js。
......
entry: {
app: ['babel-polyfill', path.resolve(__dirname, '../src/index.js')],
vendor: ['react', 'react-dom', 'babel-polyfill'],
},
resolve: { // 指定第三方库目录，减少webpack寻找时间
modules: [path.resolve(__dirname, '../node_modules')],
},
......
plugins: [
new webpack.optimize.CommonsChunkPlugin({
name: 'vendor',
minChunks: Infinity,
}),
],
......